In the previous posts we talked a little bit about monosaccharide type active pharmaceutical ingredients. The next are disaccharides: composed of two monosaccharides, that are linked by a glycosidic bond.
The most well-known, commercially available disaccharides are sucrose and lactose, but only a few have pharmacological effects and are marketed as drugs.
Lactulose (1) is a synthetic sugar, composed of galactose and fructose (4-O-β-D-Galactosyl-D-fructose) and it is used in the treatment of constipation and hepatic encephalopathy. It is not absorbed from the gastrointestinal tract (GIT) and by remaining in the digestive system causes water retention, thus softening the stool. In the colon it is fermented by the gut microbiota, producing peristalsis-stimulating and osmotic metabolites. From this fermentation comes the most common side effect –flatulence- by methane production.
There is another disaccharide that affects the GIT: sucralfate (2). It is an aluminum complex of sulfated sucrose, mainly used for the treatment of active duodenal ulcer. However, it is also used for several other stomach acid related diseases, like gastro-esophageal reflux disease (GERD) or gastritis. At low gastric pH (<4) the compound polymerizes – a white paste-like substance is formed1– then the aluminum dissociates from the sugar polymer. After the reaction, the negatively charged polymer binds to the positively charged proteins from the damaged mucosa, forming a barrier, preventing the acid to reach the damaged tissue. Its effect is local.
In the strict sense only the above mentioned disaccharides are used as active pharmaceutical agents, but if we broaden our horizon, there are lots of various disaccharides e.g. trehalose (used in artificial tears) or several disaccharides are part of glycosides with diverse pharmacological effects, like streptobiosamine (composed of L-streptose and N-methyl-L-glucosamine) is part of streptomycine, an antibiotic molecule (we will discuss the aminoglycoside type antibiotics in the next post).
What do you think? Do you know about other disaccharides that should be mentioned?
So next we’ll jump into the oligosaccharides, that will be a larger topic to discuss…
1 Brogden, R.N.; Heel, R.C.; Speight, T.M.; Avery, G.S. Sucralfate: A Review of its Pharmacodynamic Properties and Therapeutic Use in Peptic Ulcer Disease, Drugs, 1984, 27(3):194-209